At present, there are two methods for achieving confidential display. One method is based on a switchable viewing angle. In this method, a display may be switched between a wide viewing angle mode and a narrow viewing angle mode. When the display operates in the narrow viewing angle mode, only persons within a certain viewing angle range can see displayed content while persons beyond the certain viewing angle range cannot see the displayed content, thereby achieving the confidential display. Such method is defective on account of narrow observing range and poor confidentiality. The other method is to use special glasses. In related technology, liquid crystal glasses are utilized, and a four-pole double-throw electronic switch is controlled to send antiphase signals and inphase signals to the screen in a time-division manner. The antiphase signals and the inphase signals are sent alternately, or each time the antiphase signal may be sent with a probability of 50% and the inphase signal may be sent with a probability of 50%. The liquid crystal glasses are connected to the electronic switch, and are switched on when the inphase signals are sent to the screen and switched off when the antiphase signals are sent to the screen. The above method using the liquid crystal glasses is defective for the following reasons: in the case that each time the antiphase signal may be sent with a probability of 50% and the inphase signal may be sent with a probability of 50%, consecutive frames of antiphase or inphase signals may occur and then the liquid crystal glasses may be switched on or off during time corresponding to the consecutive frames; as a result, a frequency of a video signal observed by a person may be decreased and image flickering may occur.